The present invention relates to electrical supply and data transfer apparatus for normally providing electrical power from the mains of an electrical supply to a data processing system comprising several permanent store units connected to a computer, and, in response to a power supply failure, for transferring the fundamental data held in that computer into one of the permanent store units.
Recently developed data processing systems usually are highly complex assemblies in which all peripheral units are connected to at least one computer. The peripheral units exchange data with that computer according to the instructions of a program held partly in the central store (main memory) of that computer and partly in the permanent store units (for example magnetic discs or tapes) connected to that computer.
These data processing systems are usually supplied from a utility electrical distribution network at low frequency (50 to 60 Hz) and, consequently, are very sensitive to disturbances, such as micro-interruptions, transient overvoltages and power failures which could occur on that network.
These disturbances could alter or even destroy not only the information stored or being processed, but also the programs held in the central store for the purpose of that processing. These disturbances are especially irksome because they make it necessary to check the data in the central store, to run the program a second time, and to execute test programs before taking up the processing from the stage to which it has progressed just prior to the disturbances.
In order to overcome the loss of time and the possibilities of errors entailed by these operations, it was found convenient to supply the data processing system from the utility electrical supply through the intermediary of motor generator sets, each set consisting of a motor connected to the electrical power supply and an alternator drive by the motor which supplies power to the data processing system. A flywheel mounted on the motor driving shaft ensures the stabilization of the rotating speed of the set and smooths out the effects of micro-interruptions. The type of motor used on such sets can be synchronous or asynchronous.
However, in the event of a power cut, the use of a synchronous motor requires complicated and very expensive equipment in order to ensure the re-synchronization of the motor without producing interferences in the computer. In order to avoid the need for such re-synchronization equipment, a standard rated asychronous motor is preferably used. The asynchronous motor carries a flywheel and drives the input shaft of a variable slip electro-magnetic coupling. The output shaft of the coupling drives an alternator at a speed slightly less than the speed of the motor. The alternator speed is stabilized by a second flywheel. During a power cut, the first flywheel slows down from its original speed to the alternator's speed, while the coupling holds the alternator's speed to its rated value by progressively reducing the slip. However, such a solution is relatively costly, heavy and bulky. Moreover, it does not meet easily the requirements of the driving devices of the peripheral units and of the various logic and memory circuits of the computer which require different voltages and frequencies.
The present invention overcomes these difficulties and not only ensures an electrical supply to the various engineering areas of the system, (e.g., motors, logic circuits and memory store), but moreover, in case of a power cut, transfers the data held in the main memory of the system to a given permanent store unit.
One feature of the invention relates to an electrical supply and data transfer device intended to supply electrical power to a data processing system comprising at least one permanent store unit and a main memory. This data processing system is supplied with voltage from a generator means connected to the supply, the generator means characterized by the ability to supply electrical power for a predetermined time period after the electrical supply fails. A detecting device connected to the electrical supply detects power cuts on the supply and, as soon as a power cut occurs, produces a failure indicating signal. Logic means transfer data from the main memory to a selected permanent store unit in response to a gating signal produced by a selector means. The selector means responds to the failure indicating signal by generating the gating signal and by conducting electrical power from the generator means to the permanent store unit so that data are transferred from the main memory into the selected store unit between the time a power cut is detected and the time the selected store unit ceases to be energized by the generator means.